The present invention relates generally to an apparatus used to treat semiconductor wafer surfaces. More particularly, the present invention is an apparatus, for treating spinning semiconductor wafer surfaces, in which there is provided a head, for contacting the surface of the wafer, having attached thereto a first means for setting the head against the wafer surface with a selected predetermined force and a second means for temporarily and selectively altering the selected predetermined force set by the first means without altering the setting established by said first means.
Production of semiconductor devices requires the treatment of a semiconductor wafer with a number of chemical, mechanical or chemical-mechanical processing steps.
During these processing steps, even minute changes or variations in the wafer surface can produce effects that can adversely affect later processing steps and thus affect the reliability of the devices formed in the wafer. For example, such changes and variations can fail to remove contaminants or otherwise fail to appropriately condition the surface of the semiconductor wafer such that later processing steps are interfered with. When such processing steps fail they usually result in either instant or premature failure or long term degradation and shortened life of some or all or the devices produced in the wafer.
Certain of these processing steps require the use of an apparatus that can place a head, carrying a pad or brush, steeped in a suitable chemical such as a cleansing agent, adjacent to or against the surface of the wafer to treat, e.g., clean, or otherwise condition, the surface of the wafer.
In all such presently available apparatuses the force between the brush or pad carrying head and the surface, i.e., the head pressure, is substantially unknown and uncontrolled. Further the prior art apparatuses lack any means for consistently setting, maintaining or monitoring the head pressure. This lack of control of the head pressure is inherent in the prior art apparatuses because their rigid design renders them incapable of either achieving or consistently maintaining a known head pressure.
The present inventors have now found that many of such wafer processing steps require, for optimum results, that distinct head pressures be maintained and that for most process steps that the head pressure be, at least, a selected minimum pressure. The present inventors have also found that by doing so more consistent production results can be obtained.
The present inventors have also found that while many steps require this minimum head pressure other steps require that the head pressure be altered from this minimum pressure.
Therefore, it is most desirable that such semiconductor devices be fabricated using an apparatus that is capable of producing and maintaining different selected head pressures as required by the process steps.
It is also desirable, for many process steps, that the apparatus be readily and quickly capable of returning the applied head pressure to a preselected minimum head pressure.
The present invention provides a head processing apparatus having a first means that can be set to establish and provide a selected head loading or pressure, i.e., the loading or pressure between a brush or pad carrying head and a wafer surface, and a second means that can be activated to temporarily alter or adjust the selected head pressure without affecting the setting of the said first means that establishes the selected head pressure such that when said second means is deactivated, the apparatus will instantly return to the selected head pressure established by said first means.
The present invention by providing said first and second head loading means maintains better processing conditions thus causing all the processing steps performed by the apparatus to be performed under optimum and repeatable conditions.
In this way, the present invention, achieves better more consistent results and a lower defect or scrap rate.
More particularly, the present invention accomplishes these desirable results in a semiconductor wafer chemical mechanical treatment apparatus having a sectional extended arm carrying a head. The sectional arm is comprised of a fixed yoke and an elongated arm positioned in said yoke on a pivot. The elongated arm carries a first means thereon for establishing and maintaining a given loading or pressure on the head. A second means, is positioned on the yoke, adjacent to the elongated arm for temporarily altering the given loading or pressure on the head established by the first means without disturbing the setting of the first means such that when the second means is reset the given head load or pressure established by said first means is automatically restored.
Therefore it is an object of the present invention to provide a new wafer treatment apparatus which is provided with first means that can be set to create a selected head pressure between a brush and pad carrying head and a wafer surface and with second means for altering the selected head pressure as required by the process without altering the setting of the first means.
These objects, features and advantages of the present invention will be become further apparent to those skilled in the art from the following detailed description taken in conjunction with the accompanying drawings wherein: